"Analysis -- Long expected, Dell finally officially released its first line of consumer PCs with pre-installed Linux, Ubuntu 7.04, on May 24. Here's a closer look at exactly what's what in Dell's initial line of Ubuntu-powered desktops and laptops."

http://www.desktoplinux.com/news/NS5465909777.html

"Dell goes Ubuntu; "Windows tax" is $50 according to pricing"

http://arstechnica.com/news.ars/post/20070525-windows-tax-is-50-according-to-dell-linux-pc-pricing.html

Only in US store at this time. Not clear if discount on advertised systens still available if the systems are upgraded.